SALT2: using distant supernovae to improve the use of type Ia supernovae as distance indicators *,**
LPNHE, CNRS-IN2P3 and Universités Paris VI & VII, 4 place Jussieu, 75252 Paris Cedex 05, France e-mail: email@example.com
2 LAM, CNRS, BP 8, Traverse du Siphon, 13376 Marseille Cedex 12, France
3 Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H8, Canada
4 CENTRA-Centro M. de Astrofisica and Department of Physics, IST, Lisbon, Portugal
5 CPPM, CNRS-IN2P3 and Université Aix-Marseille II, Case 907, 13288 Marseille Cedex 9, France
6 University of Oxford Astrophysics, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK
7 Department of Physics and Astronomy, University of Victoria, PO Box 3055, Victoria, BC VSW 3P6, Canada
8 DSM/DAPNIA, CEA/Saclay, 91191 Gif-sur-Yvette Cedex, France
Accepted: 30 January 2007
Aims.We present an empirical model of type Ia supernovae spectro-photometric evolution with time.
Methods.The model is built using a large data set including light-curves and spectra of both nearby and distant supernovae, the latter being observed by the SNLS collaboration. We derive the average spectral sequence of type Ia supernovae and their main variability components including a color variation law. The model allows us to measure distance moduli in the spectral range with calculable uncertainties, including those arising from variability of spectral features.
Results.Thanks to the use of high-redshift SNe to model the rest-frame UV spectral energy distribution, we are able to derive improved distance estimates for SNe Ia in the redshift range . The model can also be used to improve spectroscopic identification algorithms, and derive photometric redshifts of distant type Ia supernovae.
Key words: supernovae: general / cosmology: observations
Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS. Based on observations obtained at the European Southern Observatory using the Very Large Telescope on the Cerro Paranal (ESO Large Programme 171.A-0486). Based on observations (programs GN-2004A-Q-19, GS-2004A-Q-11, GN-2003B-Q-9, and GS-2003B-Q-8) obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Particle Physics and Astronomy Research Council (UK), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), CNPq (Brazil) and CONICET (Argentina).
© ESO, 2007